An analysis of blood samples from patients of chronic fatigue syndrome has revealed substances, or 'biomarkers', indicating the condition -- a finding which is seen as a "concrete step" towards developing a diagnostic blood test.

Researchers from Cornell University, US, said that in the absence of lab tests for diagnosing the condition, doctors have to rely on patients reporting symptoms such as exhaustion, dizziness, disturbed sleep and 'brain fog'.

The team explained that when a cell dies, it leaves behind marks or "fingerprints" -- genetic material released into blood plasma, tissue injury and signs of other biological processes.